I have a piece of footage, a bird attacking cam, which has a black background. I want to be able to apply it to the footage I have shot but after exporting a premultiplied version and importing it back into after effects I find that a lot of the bird footage is transparent (not only the black section). This I know has something to do with my alpha channels but I'm unsure how to have the bird fully intact with all the (PURE) black removed and the shaded areas still visible.
I know there's an AE wiz genius out there who can help, so please do, I'm struggling to get this finished in time.
Why not just nest the comp containing the bird footage into the main comp? That's about all I can suggest at the moment, because we know NOTHING about the nature of this footage, or whether this footage has transparency. I'm assuming it does, but I don't know that for a fact.
If it's just bird footage shot on a black background, you've got your work cut out for you. You'll have to animate a mask around the bird to create transparency you seek. This is a long, painstaking, mind-numbing process called Rotoscoping.
It almost sounds like you said to yourself, "Hey, I've got this cool-looking bird footage over black! I'll just tell the computer to get rid of the black!"
You didn't take into account that there may have been areas of black on the bird itself, and the process of getting the composite you want becomes a lot tougher.
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